Laser blow-off with photodiode detection system at the helically symmetric experiment

A laser blow-off (LBO) system has been installed in the HSX stellarator to investigate impurity transport. A Nd:YAG laser is used to ablate a target area on a glass slide that has been coated with a thin film of aluminum and rapidly deposits a small, controlled quantity of aluminum atoms into HSX plasma. To study the radial propagation and confinement of the injected aluminum impurities, time-resolved emission measurements are made using a 20 channel AXUV photodiode detection system. The LBO system has achieved its design purpose, most notably the ability to make controlled impurity injection without significant perturbation to the background plasma. A detailed description of the setup as well as initial results of operation are presented.

Automated summary

The laser blow-off (LBO) system in the HSX stellarator enabled controlled injection of aluminum impurities into the plasma without significant disruption. Time-resolved emission measurements using a 20 channel AXUV photodiode detection system were performed to study the radial propagation and confinement of the injected impurities. The system has successfully achieved its design purpose and initial results indicate effective impurity transport investigations.